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Thermal relief or more copper for more current

mulfycrowh , 06-10-2022, 02:33 PM

Hi everyone,

Thermal relief helps pcb manufacturing.
But it is in a way against having more copper and more copper means more current and less heating.

What is your experience ?

Thanks.

qdrives , 06-10-2022, 03:03 PM

Yes, thermal reliefs are a double edged sword. If your application requires either high current or cooling through PCB/copper you cannot use thermal reliefs.
It is more for manual soldering, but it is a lot easier if you put the PCB on a pre-heater for such 'heavy connections'.
With products in full automatic production I have never seen a problem, even with many additional thermal via's.

robertferanec , 06-13-2022, 07:40 AM

I agree with @qdrives, thermal relief is necessary mostly in the cases when you have a through hole pin connected on multiple layers (e.g. a GND through hole pin connected to 4 internal GND planes) - in these cases it may be super hard manually solder down the pins properly if there would be no thermal relief (learned the hard way).

But if the components are soldered in the "oven" (reflow soldering), that is usually working ok even without thermal relief (the whole board is pre-heated and then slowly cooled down, thermal relief may not be necessary. Sometimes people say, if the board will not cool down equally, it may cause some soldering issues e.g. tombstoning, but we have not get this kind of complains even when our smd components are connected directly to big planes.)

qdrives , 06-13-2022, 03:46 PM

Originally posted by robertferanec

learned the hard way

Here literally as the solder remains hard ;-)

Tombstoning also happens due to an imbalance between the amounts of copper between the two pads. When one is in a polygon pour while the other has a 0.2mm track connected to it..

mulfycrowh , 07-19-2022, 05:57 AM

Hi everyone,

I am using AD22.
I noticed that when setting the air gap width to 0 mm, I always get the thermal relief.
It was OK in AD21.

Thanks for help.

qdrives , 07-19-2022, 01:33 PM

Air gap to 0mm is "direct connection". I can imagine that Altium treats 0mm as the standard 0.254mm.
If you do not want a thermal relief, set the connection to "direct connection".